This invention relates to a heat pump assembly comprising a refrigeration circuit including a condenser, a compressor and an evaporator, and further comprising a heating circuit in communication with the condenser and including a space heat exchanger for the heating of space by heat absorbed from the capacitor. The heating circuit further includes the internal combustion engine, a heat exchanger in communication with an exhaust pipe extending from the engine, and a retarder driven by the engine for the torque loading of same, the space being thereby further heated by the engine and the emissions therefrom.
Generally, heat pump assemblies which operate with compressors driven by internal combustion engines, are known in the art. If outside or ambient air is utilized as the heat source for the heat pump, the total heat required for the space to be heated, such as a house, even when the temperature of the outside air is extremely low (e.g., -15.degree. C.), can be delivered only if the refrigerant compressor is geared to accommodate such low outside air temperature. Consequently, for those outside air temperature ranges which prevail most of the time, the capacity of the compressor is too high so that even if the rotational speed of the compressor is reduced, an on-off control must be employed for fairly high outside temperatures in order to run the compressor at the low capacity required. However, an on-off control results in standstill and starting losses and moreover, reduces the service life of the compressor and of the internal combustion engine.
Therefore, it is advisable to properly gear the refrigerant compressor to the outside temperature range which prevails most of the time. This is achieved by installing an auxiliary heating system to accommodate the occurences of extremely low outside temperatures. However, such a system requires considerable capital outlay which may remain unused for a large portion of the heating period.
In German published application No. 27 28 273, this problem is overcome by gearing the capacity of the compressor to the annual operating range which is used most of the time, and by feeding the dissipated heat of the internal combustion engine to the heating circuit. Within the range of low outside temperatures, an auxiliary unit, such as a fluid brake or a generator loaded with heat resistors, is switched on for loading the internal combustion engine. Thus, the engine operates at a high power loss creating heat which can be transferred to the heating circuit, and the fluid brake or heat resistors form supplementary sources of heat to warm up the heating circuit.
However, the drawbacks in the use of such a fluid brake include its mechanical sensitivity as well as the dependence of its performance on the properties of the fluid employed in a useful circuit. This interferes with adequate adjustability, which can be achieved only with a cost-intensive system. And, the use of a resistor-loaded generator requires complex and expensive switchgear in the electric circuit for the gradual or continuous regulation of the load.